In a society increasingly dependent on computer systems, power conservation has become an important issue. Personal computers are therefore being designed to minimize power consumption. In a power-saving computer there may be as many as four or more operating modes with greatly varying power consumption. A first mode, which may be called peak mode, provides the power-on surge, which may be, for example, 90 watts. A second mode, which may be called normal mode, supports routine computer operations with full expansion capabilities at, for example, about 50 watts. A third mode, which may be called suspend mode, powers down computer processing activity but retains random access memory (RAM) at a lower power level, which in this example may be about 10-15 watts. A fourth mode, which may be called standby mode, powers down everything except a wakeup circuit, in this example about 1-2 watts.
To work at optimum efficiency the ratio of minimum to maximum load for a power supply in a personal computer should not exceed about 1:6. But, as described above, a power-saving computer may consume as little as 1-2 watts in standby mode and 90 watts or more during power-on, a ratio of as much as 1:90 or higher.
As a power conservation measure, simple timer switches can be used to automatically turn computers off after hours and turn them back on at the start of the next business day. But the use of such automatic timer-switch controls is not without problems. Workers may not always be ready to save their work before the designated shutdown time and important data may be lost. Also, rigidly imposed shutdown times may have an adverse effect on worker creativity. Often having "just a few more minutes" is just what is needed to finish a job. In addition, workers who may come in early or are authorized to work on other-than-normal business hours may find they cannot access their computer systems.
What is needed is an automatic timer-controlled system that is both flexible and energy-efficient. Such a system should track individual computer activity throughout the work day and automatically adjust startup and shutdown times to users schedules. Continuous tracking and adjustments would allow companies to provide reasonable and comfortable time boundaries for each employee. Also adjustments could easily be made for variables such as shift work, holidays, and Daylight Savings Time.